Gastro-esophageal reflux disease (GERD) is a common problem and is expensive to manage in both primary and secondary care settings. This condition results from exposure of esophageal mucosa to gastric acid and bile as the gastro-duodenal content refluxes from the stomach into the esophagus. The acid and bile damages the esophageal mucosa resulting in heartburn, ulcers, bleeding, and scarring, and long term complications such as Barrett's esophagus (pre-cancerous esophageal lining) and adeno-cancer of the esophagus. Patients with GERD may only experience symptoms during the day, referred to as diurnal GERD, and may not experience any GERD symptoms at night, referred to as nocturnal GERD. Diurnal or daytime or upright GERD has been associated with tLESR, and may be diagnosed where a patient has symptoms of heartburn, regurgitation or both.
The severity of GERD increases progressively from postprandial to upright, to supine, to bipositional reflux. A structural defect as reflected by decreased LES pressure and length is also significantly less common with postprandial and upright reflux. The improved esophageal sensation associated with improved saliva production that neutralizes the refluxed acid and increased clearance of the refluxate aided by gravity results in lesser esophageal damage.
Lifestyle advice and antacid therapy are advocated as first line treatment for the disease. However, since most patients with moderate to severe cases of diurnal GERD do not respond adequately to these first-line measures and need further treatment, other alternatives including pharmacological, endoscopic, and surgical treatments are employed.
The most commonly employed pharmacological treatment is daily use of H2 receptor antagonists (H2RAs) or proton-pump inhibitors (PPIs) for acid suppression. Since gastro-esophageal reflux disease usually relapses once drug therapy is discontinued, most patients with the disease, therefore, need long-term drug therapy. However, daily use of PPIs or H2RAs is not universally effective in the relief of diurnal GERD symptoms or as maintenance therapy. Additionally, not all patients are comfortable with the concept of having to take daily or intermittent medication for the rest of their lives and many are interested in nonpharmacological options for managing their reflux disease.
Several endoscopic procedures for the treatment of diurnal GERD have been tried. These procedures can be divided into three approaches: endoscopic suturing wherein stitches are inserted in the gastric cardia to plicate and strengthen the lower esophageal sphincter, endoscopic application of energy to the lower esophagus, and injection of bulking agents into the muscle layer of the distal esophagus. These procedures, however, are not without their risks, besides being technically demanding and involving a long procedure time. As a result, these procedures have largely been discontinued.
Open surgical or laparoscopic fundoplication is also used to correct the cause of the disease. However, surgical procedures are associated with significant morbidity and small but not insignificant mortality rates. Moreover, long-term follow-up with patients treated by surgery suggests that many patients continue to need acid suppressive medication. There is also no convincing evidence that fundoplication reduces the risk of esophageal adenocarcinoma in the long term.
While electrical stimulation has been suggested for use in the treatment of diurnal GERD, an effective electrical stimulation system has yet to be demonstrated. In particular, the prior art teaches that effective electrical stimulation requires active, real-time sensing for a patient's swallow and, based on a sensed swallow, to immediately cease stimulation. For example, certain prior art approaches require the constant sensing of certain physiological changes in the esophagus, such as changes in esophageal pH, to detect acid reflux and/or esophageal motility and, based on such sensed changes, initiating or terminating an electrical stimulation to instantaneously close or open the LES, respectively, thereby avoiding an acid reflux episode. Other prior art approaches require continuous stimulation with sensing for swallow and stopping stimulation to allow for normal swallow to happen. This creates a complex device and has not proven to be feasible or effective in practice.
Therefore, there is still a need for a safe and effective method of treatment that can help alleviate symptoms of diurnal GERD in the long term, without adversely affecting the quality of life of the patients. In particular, there is a need for simple, efficient diurnal GERD device and treatment methods that do not inhibit a patient from swallowing and do not rely on an instantaneous response from the patient's LES to avoid episodes of acid reflux. There is a need for treatment protocols and devices which are programmed to implement such protocols, which can be easily programmed and do not require complex physiologic sensing mechanisms in order to operate effectively and safely. Moreover, there is not only a need for better devices in stimulation based therapies, but there is also a need for a safe and minimally invasive method and system that enables easy and expeditious deployment of such devices at any desired location in the body.
It is further desirable to have a system for the treatment of diurnal GERD which includes a stimulator and an optional sensor adapted to be placed in a patient's LES tissue.
It is further desirable to have a system for the treatment of diurnal GERD which includes an active implantable medical device (AIMD) and temporary sensor adapted to be placed in a patient's GI lumen where the sensors are designed to naturally dissolve or pass out through the lumen and the AIMD is adapted to dynamically acquire, process, measure the quality of, and use sensed data only when the sensor is present.
It is further desirable to have a system for the temporary treatment of diurnal GERD which includes an AIMD, which is adapted to be placed in a patient's GI lumen, designed to naturally dissolve or pass out through the lumen, and is adapted to deliver electrical stimulation to tissue at or in the vicinity of the LES. Such temporary stimulation scheme can additionally be used for pre-screening of patients likely to benefit from permanent stimulation.
It would further be desirable for the stimulator to use periodic or occasional sensing data to improve the treatment of diurnal GERD by dynamically detecting when a sensor is present, determining when a sensor is transmitting, or capable of transmitting, data, and processing the sensed data using an application having a special mode which opportunistically uses the sensed data to change stimulation parameters.
It is also desirable to automate the setting or calibration of some or all device parameters in order to reduce the need for medical follow-up visits, reduce burdens on healthcare providers and patients, decrease the rate of programming mistakes, and improve outcomes, thereby improving the treatment of diurnal GERD.
In addition, patients suffering from GERD, nocturnal GERD, diurnal GERD, or transient lower esophageal sphincter relaxation (tLESR), typically have their eating habits impaired because of the associated reflux events. As a result, these individuals often experience fluctuations in weight, or actively lose weight, since they are unable or unwilling to ingest much food.
Although often not completely effective, conventional treatments, such as the daily use of H2 receptor antagonists (H2RAs) or proton-pump inhibitors (PPIs), may suppress acid reflux to some degree. In such cases, a GERD patient may find that, as symptoms improve, he or she begins to eat more and gain weight. Weight gain is therefore an unintended and undesirable consequence of conventional GERD treatments.
It is therefore also desirable to have a treatment for GERD, nocturnal GERD, diurnal GERD, or tLESR that, while successfully reducing or eliminating acid reflux, avoids or minimizes the weight gain which typically accompanies the successful treatment of acid reflux.